Heretofore, in sorting bearings such as needle bearings or other round bearings they are allowed to slide down between two rotating cylinders whose axes are mounted in a diverging manner so as to provide a gradually enlarging gap between the cylinders.
As the bearings slide down the cylinders they drop through the cylinders at the point the width of the gap exceeds the diameter of the bearing. If the cylinders were perfectly cylindrical and could be driven while maintaining this desired gap there would be no problem in sorting bearings to accurate and high tolerances. However, it is substantially impossible to make a perfectly cylindrical cylinder or roll and, accordingly, while the variances may not be noticeable to the eye, when sorting bearings to high tolerances such as 10 millionths of an inch, any variance in the roundness of one or the other of the cylinder causes changes in the width of the sorting gap.
An example of a sorting device which solves many of these problems is disclosed in applicant's U.S. Pat. No. 4,172,527. The sorter disclosed in this patent permits sorting of bearings to tolerances of 0.000010 of an inch. However, it has been found that even with the sorter of this patent that temperature variations along the length of the cylinder will affect the sorting capacity of the sorter. It has been found that this temperature variation is the greatest when the sorter is initially started and continues for the first twenty four hours of operation. After twenty four hours it has been found that the temperature of the rolls stabilizes and the sorter sorts within the necessary tolerances.
In applicant's U.S. Pat. No. 4,128,282, is shown a counter balance bearing assembly for supporting the sorting cylinders of a sorting device such as that shown in applicant's Pat. No. 4,172,527, noted above. The bearing support disclosed in this patent is basically the same as that disclosed in applicant's Pat. No. 4,172,527. These bearings generate heat within the sorting roller or cylinder, which causes variations in the sorting gap between the cylinders and, therefore, affects the sorting accuracy of the sorting device.